1. Field of the Invention
The present invention relates generally to an insulated liner and, more particularly, to an insulated liner with a thermally insulative medium disposed between the liner and the cylinder wall in order to reduce the thermal conductivity between the liner and the cylinder block.
2. Description of the Prior Art
Those skilled in the art of engine design are familiar with the use of cylinder liners which are disposed within the cylinders of an engine block. Typically, the cylinder liner is made of a different material than the engine block.
U.S. Pat. No. 5,150,668, which issued to Bock on Sep. 29, 1992, describes a cylinder liner with a coolant sleeve. The liners must be adequately cooled to obviate oil degradation, carbon packing in the ring area, and piston seizure. The engine includes a block which cooperates with the cylinder liners to define an upper and lower axially spaced coolant chambers. A sleeve is located in a groove defined in the cylinder liner and disposed between the upper and lower coolant chambers. The sleeve and the cylinder liner define a plurality of circumferentially spaced venturi throats. The venturi throats provide a relative long flow path and controls the flow rate of the coolant being communicated from the lower coolant chamber to the upper coolant chamber in order to dissipate heat away from the cylinder liner.
U.S. Pat. No. 5,251,578, which issued to Kawauchi et al. on Oct. 12, 1993, describes a cooling system for an internal combustion engine. The cooling system is able to realize a cooling effect matching a distribution of incoming heat of a cylinder liner. A plurality of annular grooves is formed on an outer surface of the cylinder liner, and a passage connecting the annular grooves is also provided. An introducing passage part is formed between an inlet passage of a coolant and the uppermost annular groove. A curved portion is provided to the introducing passage part. A flow direction of the coolant flowing into the introducing passage part is smoothly changed so as to flow along a direction of a passage connecting the annular grooves. An amount of coolant flowing into the annular grooves located lower than the uppermost annular groove is increased appropriately.
U.S. Pat. No. 5,582,144, which issued to Mizutani on Dec. 10, 1996, describes a dry cylinder liner for internal combustion engines. The liner has a flange at the outer circumference of the upper part of a liner barrel, and also has a grind relief groove formed below the flange at the outer circumferential surface of the liner barrel. The upper surface and the lower surface of the flange are coated with a coating film comprising a heat resistant resin containing a solid lubricant. The coating film may also be applied to only the lower surface of the inner flange. This coating film may also be applied to the upper surface of a cylinder block that contacts the lower surface of the liner flange.
U.S. patent application Ser. No. 09/953,867, which was filed by Negishi et al. on Sep. 18, 2001, describes a cooling system for a cylinder liner. An oil groove is formed on a top deck of a cylinder block to surround a cylinder liner such that the groove does not substantially extend deeper beyond cylindrical load plane of a seal ring on a head gasket, which prevents a clamp-down load of the gasket from acting as a bending load on an upper wall of the groove. The cylinder liner, which receives a great amount of heat transmitted from a top ring on a piston when the latter is near and at its top dead center position, can be effectively cooled without deformation of the cylinder block and/or the cylinder liner even if the top ring is positioned at an elevated position for the purpose of attaining a high compression ratio.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.
Many cylinder liner structures are particularly configured to provide improved cooling of the liner. However, in certain applications of internal combustion engines, it is important that the cylinder liner be allowed to increase in temperature beyond that which would normally be controlled by a cooling system. This is particularly true when the internal combustion engine is used in a marine environment and with an open cooling system that draws water from a body of water and circulates that water through the cooling passages of the engine.
It would therefore be significantly beneficial if a configuration could be provided for a cylinder liner which allowed the cylinder to achieve higher temperatures than would otherwise result from the use of cooling water in an open cooling system. It would also be beneficial if the cooling water could be maintained at a lower temperature than the desired temperature of the cylinder liners.